I would like to reiterate that you look at your PSU first. Secondly,
Take your time and watch the deal sites (logicbuy, dellcoupons) --- as has been suggested ATI HD 4850s and NVIDIA GTS 250s have been dipping into this price range on special offers. They are getting cleared out of inventory for the newer cards. Last week newegg had a sapphire 4850 for $79--but its back up to $94 now. The cards will be back soon though.
That said, the 5670 or 9800GT would be more than enough for playing WOW or anything like it. Either would be an excellent choice -- and are better than the other options you suggested.